The present invention relates to computer systems. In particular, the present invention relates to input devices for computer systems.
In many computer systems, users are able to control functions and select displayed items using a pointing device such as a mouse. Information about the status of a mouse, such as mouse movement and the activation of switches on the mouse, is periodically provided to the computer by the mouse. This information is usually delivered in data packets and is generally received by software programs known as mouse drivers, which provide an interface between the hardware of the mouse and the operating system of the computer. In some systems, when the mouse driver receives a data packet, it generates one or more mouse messages that convey the current status of the mouse including what buttons are depressed on the mouse.
The mouse messages generated by the mouse driver are typically sent to the application that has a display window directly below a mouse cursor, or caret, on the screen. However, in some computer architectures, other applications can receive a mouse message by registering a message hook with the operating system. Under these architectures, the operating system keeps a list of registered message hooks and when the operating system receives a mouse message, it sequentially invokes the message hooks. Each message hook in the list will be invoked unless one of the message hooks consumes the mouse message by returning a value to the operating system that tells the system to stop invoking message hooks in the list and to not send the mouse message to the application that has a window below the mouse cursor.
Currently, mice generally have two buttons or three buttons. Therefore, applications have been written to accept mouse messages indicating events relating to at most three buttons. They generally do not have the ability to deal with any additional button closure events. In light of this, it has not been possible to implement more than three buttons on a mouse in such a way that additional functions can be invoked from currently available applications by depressing one of the additional buttons.